Snowpack 2.10.0 seems to have broken snowpack build --watch

[benoitg]

The process exits without actually waiting for changes:

./node_modules/.bin/snowpack build --watch
[snowpack] ! building source…
[snowpack] ✔ build complete [1.31s]
[snowpack] ! installing dependencies…
[snowpack] Warning: 1+ circular dependencies found via "node_modules/d3-selection/src/selection/index.js".
[snowpack] ✔ install complete [25.35s]
[snowpack] Watching for changes...
benoitg@benoitg-Yoga-C940:~/development/agile-u$ 

[NfNitLoop]

Ha! I ran into this too. I was writing up a larger bug report for other oddities with snowpack build --watch:

I'm using snowpack build --watch for my dev. workflow (since I'm serving the
JS through another web server) and there are a few things that seem to not be
working correctly with that command (option?).

Steps to reproduce

Create a blank project:

npx create-snowpack-app example-snowpack --template @snowpack/app-template-blank

Add this to package.json's scripts section:

"watch": "snowpack build --watch",

Start it up:

npm run watch

And here's the output:

C:\Users\cody\programs\example-snowpack>npm run watch

> @ watch C:\Users\cody\programs\example-snowpack
> snowpack build --watch

[snowpack] ! building source…
[snowpack] ✔ build complete [0.02s]
[snowpack] ! installing dependencies…
[snowpack] ✔ install complete [0.12s]
[snowpack] Watching for changes...

C:\Users\cody\programs\example-snowpack>

Wait, what? That's not even the bug I was trying to show off! It looks like
in v2.10, --watch just exits immediately. Oops.

Reproducing the issues in v2.9.3

Ok, downgrade package.json to use:

"snowpack": "=2.9.3"

And

npm install

Also, it turns out this failure requires TypeScript, so rename index.js to
index.ts.

And now this works (and continues to wait):

npm run watch

... BUT, try editing your index.ts and saving a file with broken javascript.
(I just throw in an unmatched { somewhere.) You'll get something like:

[@snowpack/plugin-esbuild] Error: Transform failed with 1 error:
C:\Users\cody\programs\example-snowpack\src\index.ts:16:0: error: Unexpected end of file
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @ watch: `snowpack build --watch`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the @ watch script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\cody\AppData\Roaming\npm-cache\_logs\2020-09-02T03_17_25_545Z-debug.log

... and Snowpack exits. (I'd expect it to keep running so that I could re-save
my file w/ the correct Javascript. Sometimes I don't even have the window
visible since I'm working in my editor and browser, so it can take minutes
to realize that Snowpack is no longer refreshing my sources for me.)

One more failure mode

In my setup, I've got a custom build step to generate some javascript files
as snowpack starts up. If THOSE commands fail, I'd expect Snowpack to fail and
exit immediately -- if it can't build the initial scripts, there's no reason to
keep watching.

To reproduce:

Add this plugin entry to snowpack.config.json to simulate a failing command:

  "plugins": [
    [
        "@snowpack/plugin-run-script",
        {
            "cmd": "abracadabra"
        }
    ]
  ]

Make sure to remove invalid JavaScript from your index.ts from the previous
example.

Now, npm run watch shows the errors, but for some reason keeps running:

C:\Users\cody\programs\example-snowpack>npm run watch

> @ watch C:\Users\cody\programs\example-snowpack
> snowpack build --watch

[snowpack] [abracadabra] 'abracadabra' is not recognized as an internal or external command,
operable program or batch file.
[snowpack] [abracadabra] Error: Command failed with ENOENT: abracadabra
spawn abracadabra ENOENT
'abracadabra' is not recognized as an internal or external command,
operable program or batch file.
[snowpack] ! building source…
[snowpack] ✔ build complete [0.02s]
[snowpack] ! installing dependencies…
[snowpack] ✔ install complete [0.12s]
[snowpack] Watching for changes...

There's no point in starting watch mode if my dependencies couldn't be built.
Additionally, if I had many build scripts, later build scripts could fail as
a result of the prior one failing. Or, their output could cause the first
error to scroll off screen meaning I might spend time trying to debug things in
the browser/code that were due to the broken command.

[FredKSchott]

@benoitg @NfNitLoop thanks for catching this! You're right, there was 1 regression introduced by 2.10.0, and a couple of longer-standing issues here (broken run scripts don't kill the build, broken files do kill the build, even in watch mode).

Fixes for all added here: #981

[NfNitLoop]

Whoah, that was fast! Thank you! 😄

[FredKSchott]

np! this was an obvious regression, worth a quick fix as soon as we can merge it. Thanks for reporting, not sure I would have seen the "run scripts don't break the build" issue without your comment.